master: fix reload of config

As helmut noticed on IRC, some vars were not replicated when refreshing the
config (such as $config->{cgitmpdir}). This patch fixes that.

That it is only a slightly edited version of what he proposed, mostly for
clarity.

This patch is made obsolete by 6d62e6b0782ecfa0f4e0c2bec14434d675734962, which
rewrites the offending code, but it is only in 2.0.10+. That one is the one
that does fix #1289.

Closes: D:742203